Authors:

Zhun-Yong Ong(University of Illinois at Urbana-Champaign)

Duane Johnson(University of Illinois at Urbana-Champaign)

In alloys the atomic short-range order (SRO) indicates the
nascent ordering to which the disordered alloy is tending at high
temperatures. Direct first-principles prediction based upon
KKR-CPA and mean-field thermodynamics have been successful in
predicting system-specific SRO [1], if, at a
minimum, corrections are included to satisfy the diffuse
scattering sum rule in k-space. However, such models do not
account for k-dependence of the corrections. Here, we present an
analytic generalization to multicomponent alloys that includes
``cyclic diagrams'' [2,3] for composition,
temperature, and k-dependent corrections to SRO. We first explore
the improvement to SRO in model fcc ternary alloys via the
generalized Ising model. We find that there is much better
agreement to Monte Carlo simulations than with standard
Bragg-Williams with(out) Onsager corrections. Then we implement
this within the KKR-CPA linear-response theory of
SRO.\Footnote{Work was supported by DOE (Award DEFG02-03ER46026
and NSF (DMR-0325939).}
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[1] J.B. Staunton, D.D. Johnson, and F.J. Pinski,
Phys. Rev. Lett. 65, 1259 (1990); Phys. Rev. B 50, 1450 (1994);
ibid, 57, 15177 (1998).
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[2] R. Brout, Phys. Rev. 115, 824-835 (1959).
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[3] R.V. Chepulski, et al, Phys. Rev. 65, 064201-7 (2002).

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.MAR.R1.4